RESUMO
This chapter is about basic conditions of seeing motion (mostly of single objects in the frontoparallel plane. It emphasizes the richness and challenge of phenomena in motion perception. Apart from the distinction between afferent (retinal) and efferent (oculomotor) mechanisms, motion percepts can results from real (object) motion as well as from various forms of apparent motion (stroboscopic or phi motion, induced motion, autokinesis). Further intriguing motion phenomena include motion contrast and assimilation, motion adaptation and after effects, and velocity transposition. Finally, anticipatory performance of motion extrapolation is considered as a dynamic case of a modal perceptual completion, indicating that visual motion is closely related to action.